Yes, Klipsch always orders from Sonion. They've never worked with Knowles.
Outwardly, it's code-named the KG926, but that doesn't mean anything to anyone. In terms of form factor and electroacoustic properties (FR, impedance, THD pattern, etc.), it's most similar to the 26A005/8, but it may not be identical. If anything the KG926 is the progenitor to the 26A005/8, as it came to market earlier.
However, the Sleek Audio SA6/CT6 are confirmed to utilize the 26A005/8, and with some tweaks, the SA6 can be tuned to measure very similarly to the X10, with matching first and second resonance points, suggesting that the two share at least a similar driver family.
Thanks to both of you!
Reason I ask is because I sent a klipsch x10i into be reshelled aaages ago. Had fit issues, but the sound wasn't what I remembered and it seems to be for good reason!